… most expensive queries, in total execution time. By the way, the slow query logs in the stock MySQL server are extremely limited, and… may be run seldom but take a long time to finish. And it’s important to focus on ones that can give… backups, for example) read over it once again and make sure I didn’t miss anything important or write something in a…
Post: Why you should ignore MySQL's key cache hit ratio
February 28, 2010 By 28 Comments
… when you start to assign any importance to this ratio. The MySQL manual doesn’t fall into this …time measurements, which you should, you will eventually arrive at this question. “I have a query I know is slow… makes no sense, why wouldn’t you obsess over it? What about InnoDB tuning? You might be …
Post: DROP TABLE and stalls: Lazy Drop Table in Percona Server and the new fixes in MySQL
June 22, 2012 By 33 Comments
…important and the major differences in the two implementations is the use of buffer pool mutex in Oracle MySQL… slow log by setting long_query_time to 0. Then for analysis purposes the queries in the slow…whenever table is dropped, MySQL 5.5.23 does show an improvement over MySQL version prior to 5.5…
Post: Goal driven performance optimization
December 22, 2008 By Leave a Comment
…slow but it is hard to go back from them to what is really important…mysql> select count(*),avg(wtime),avg(utime/wtime) cpu_ratio, avg(mysql_time/wtime) mysql_ratio ,avg(sphinx_time/wtime) sphinx_ratio, avg((wtime-mysql_time-sphinx_time…its worst times so it is very good to plot some graph over time. …
Post: Updated msl (microslow) patch, installation walk-through!
April 20, 2008 By 17 Comments
…even more important the patch is available for all the recent MySQL releases. To…query execution times into the slow log. Originally MySQL database offered a second time resolution …time was 0.005s or 0.9s, which can make a substantial difference for the database and application performance. Over time…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 141 Comments
…work well for MySQL and other way around. Even storage engines have very important differences which can affect…to reach 100 times difference. Here is little illustration I’ve created the table with over 30 millions…bound can be very slow. One of the reasons elevating this problem in MySQL is lack of …
Post: Realtime stats to pay attention to in Percona XtraDB Cluster and Galera
November 26, 2012 By 4 Comments
…report, and I thought I’d go over some of the status variables …the cluster section, and it’s important to understand that this tool …This is the amount of time since the last time SHOW GLOBAL STATUS was …a general indicator that flow control is slowing replication (and hence overall cluster writes)…
Post: New SpecJAppServer results at MySQL and Sun.
November 12, 2008 By Leave a Comment
…= FILE log-slow-queries=/tmp/mysql-slow.log long_query_time = 1 innodb_data_home_dir = /data/mysql/var innodb_… there were no slow queries it just was left in tact. Other important settings: transaction-isolation = READ-… why not ZFS ? The ZFS MySQL success story is all over across Sun’s blogs, so …
Post: MySQL 5.6 vs MySQL 5.5 and the Star Schema Benchmark
March 11, 2013 By 7 Comments
… very easy to define an OLAP cube over a star schema, so they are… IO is slow (when the FS cache is cold, IO to slow IO subsystem … LRU, a full table scan pushes out important hot pages from the buffer pool …time=0; mysql> set global innodb_old_blocks_time=0; Query OK, 0 rows affected (0.00 sec) mysql…
Post: Side load may massively impact your MySQL Performance
November 13, 2011 By 7 Comments
…mysql –mysql-host=localhost –mysql-table-engine=innodb –mysql-db=test –oltp-table-name=md_cache_test_small –oltp-table-size=1100000 –mysql-user=msandbox –mysql…time so setting innodb_old_blocks_time variable to some value will prevent important…
